Emulsions are stable dispersions of microscopically visible droplets of one liquid or semi-solid substance in another liquid or semi-solid substance with which it is immiscible. Suspended solid particles may be present in either or both of the liquids and/or semi-solid substances. A recent resurgence of interest in emulsification has derived out of the findings that a small proportion of water or alcohol dispersed in oil will burn with higher efficiency and lower production of air pollutants than will the pure liquid fuel oil or gasoline.
It is possible to burn mixtures of gasoline and alcohol in internal combustion engines and it is also possible to burn these mixtures in furnaces for heating and power generation. However, alcohol and oil are immiscible and it is necessary to emulsify these two fuels into a stable emulsion in order to achieve satisfactory operation of existing units. Alcohol, of course, is a renewable resource which can be made available in large quantity from industrial fermentation of agricultural residues and the like.
Creating emulsions by sonic or ultrasonic waves is known per se. For example, see U.S. Pat. No. Re. 29,161. The device as disclosed in said patent is not conducive to large flow rates. For example, said patent refers to a flow rate on the order of about 80 liters per hour. Adequate attention has not been given by previous experimenters to the effects of standing waves in ultrasonic fields which are able to cause agglomeration of droplets which have already been dispersed and to the need for initially creating a large interfacial surface and then using ultrasonics to disrupt this created surface into many, many fine droplets. There is a need for an emulsifier operable in the sonic or ultrasonic range but capable of handling large throughputs including materials which may include a slurry and without the need for premixing the materials.